We will take a genetic approach to dissect the neuronal circuitry that underlies behavioral aversion of UV, using the Drosophila egg-laying site as our model system. We aim to identify and characterize both the critical sensory neurons and their post-synaptic targets that govern UV aversion. In addition, we will also assess the roles of neuro-modulatory neurons in adjusting the strength of UV aversion via modulating the communication between the specific sensory and central neurons we identified. PUBLIC HEALTH RELEVANCE: The ability to detect, assess, and respond properly to aversive stimuli is essential for animal survival and reproductive success; failure to sense significant threats causes bodily harm while unchecked sensitivity to mild aversive stimuli may incur opportunity loss as well as stress-induced mental illness. Given that the channel, neuropeptide, and neuro-modulatory systems we are investigating in our proposal all appear to be conserved across species, our findings will likely shed light on how stress is processed in humans.